/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
*
- * Copyright 1998-2008 The OpenLDAP Foundation.
+ * Copyright 1998-2012 The OpenLDAP Foundation.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
/* (Theoretical) max number of pending requests */
#define MAX_PENDING (INT_MAX/2) /* INT_MAX - (room to avoid overflow) */
+/* pool->ltp_pause values */
+enum { NOT_PAUSED = 0, WANT_PAUSE = 1, PAUSED = 2 };
+
/* Context: thread ID and thread-specific key/data pairs */
typedef struct ldap_int_thread_userctx_s {
ldap_pvt_thread_t ltu_id;
void *ltt_arg;
} ldap_int_thread_task_t;
+typedef LDAP_STAILQ_HEAD(tcq, ldap_int_thread_task_s) ldap_int_tpool_plist_t;
+
struct ldap_int_thread_pool_s {
LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
/* ltp_active_count <= 1 && ltp_pause */
ldap_pvt_thread_cond_t ltp_pcond;
+ /* ltp_pause == 0 ? <p_pending_list : &empty_pending_list,
+ * maintaned to reduce work for pool_wrapper()
+ */
+ ldap_int_tpool_plist_t *ltp_work_list;
+
/* pending tasks, and unused task objects */
- LDAP_STAILQ_HEAD(tcq, ldap_int_thread_task_s) ltp_pending_list;
+ ldap_int_tpool_plist_t ltp_pending_list;
LDAP_SLIST_HEAD(tcl, ldap_int_thread_task_s) ltp_free_list;
/* The pool is finishing, waiting for its threads to close.
/* Some active task needs to be the sole active task.
* Atomic variable so ldap_pvt_thread_pool_pausing() can read it.
+ * Note: Pauses adjust ltp_<open_count/vary_open_count/work_list>,
+ * so pool_<submit/wrapper>() mostly can avoid testing ltp_pause.
*/
volatile sig_atomic_t ltp_pause;
/* Max number of threads in pool, or 0 for default (LDAP_MAXTHR) */
int ltp_max_count;
- /* Max number of pending + paused requests, negated when ltp_finishing */
+ /* Max pending + paused + idle tasks, negated when ltp_finishing */
int ltp_max_pending;
- int ltp_pending_count; /* Pending or paused requests */
- int ltp_active_count; /* Active, not paused requests */
- int ltp_open_count; /* Number of threads */
+ int ltp_pending_count; /* Pending + paused + idle tasks */
+ int ltp_active_count; /* Active, not paused/idle tasks */
+ int ltp_open_count; /* Number of threads, negated when ltp_pause */
int ltp_starting; /* Currenlty starting threads */
- /*
- * State maintained to reduce the time ltp_mutex must be locked
- * in ldap_pvt_thread_pool_<submit/wrapper>().
+ /* >0 if paused or we may open a thread, <0 if we should close a thread.
+ * Updated when ltp_<finishing/pause/max_count/open_count> change.
+ * Maintained to reduce the time ltp_mutex must be locked in
+ * ldap_pvt_thread_pool_<submit/wrapper>().
*/
-
- /* >0 if paused or we may open a thread, <0 if we should close a thread. */
- /* Updated when ltp_<finishing/pause/max_count/open_count> change. */
int ltp_vary_open_count;
# define SET_VARY_OPEN_COUNT(pool) \
((pool)->ltp_vary_open_count = \
- (pool)->ltp_open_count)
};
+static ldap_int_tpool_plist_t empty_pending_list =
+ LDAP_STAILQ_HEAD_INITIALIZER(empty_pending_list);
+
static int ldap_int_has_thread_pool = 0;
static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
ldap_int_thread_pool_list =
pool->ltp_max_pending = max_pending;
LDAP_STAILQ_INIT(&pool->ltp_pending_list);
+ pool->ltp_work_list = &pool->ltp_pending_list;
LDAP_SLIST_INIT(&pool->ltp_free_list);
+
ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
-#if 0
- /* THIS WILL NOT WORK on some systems. If the process
- * forks after starting a thread, there is no guarantee
- * that the thread will survive the fork. For example,
- * slapd forks in order to daemonize, and does so after
- * calling ldap_pvt_thread_pool_init. On some systems,
- * this initial thread does not run in the child process,
- * but ltp_open_count == 1, so two things happen:
- * 1) the first client connection fails, and 2) when
- * slapd is kill'ed, it never terminates since it waits
- * for all worker threads to exit. */
-
- /* start up one thread, just so there is one. no need to
- * lock the mutex right now, since no threads are running.
+ /* Start no threads just yet. That can break if the process forks
+ * later, as slapd does in order to daemonize. On at least POSIX,
+ * only the forking thread would survive in the child. Yet fork()
+ * can't unlock/clean up other threads' locks and data structures,
+ * unless pthread_atfork() handlers have been set up to do so.
*/
- pool->ltp_open_count++;
- SET_VARY_OPEN_COUNT(pool);
-
- ldap_pvt_thread_t thr;
- rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
-
- if( rc != 0) {
- /* couldn't start one? then don't start any */
- ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
- LDAP_STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
- ldap_int_thread_pool_s, ltp_next);
- ldap_int_has_thread_pool = 0;
- ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
- ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
- ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
- ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
- LDAP_FREE(pool);
- return(-1);
- }
-#endif
*tpool = pool;
return(0);
pool->ltp_pending_count++;
LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, task, ltt_next.q);
- if (pool->ltp_pause) {
- ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
- return(0);
- }
- ldap_pvt_thread_cond_signal(&pool->ltp_cond);
+
+ /* true if ltp_pause != 0 or we should open (create) a thread */
if (pool->ltp_vary_open_count > 0 &&
pool->ltp_open_count < pool->ltp_active_count+pool->ltp_pending_count)
{
+ if (pool->ltp_pause)
+ goto done;
+
pool->ltp_starting++;
pool->ltp_open_count++;
SET_VARY_OPEN_COUNT(pool);
}
/* there is another open thread, so this
* task will be handled eventually.
- * continue on, we have signalled that
- * the task is waiting.
*/
}
}
+ ldap_pvt_thread_cond_signal(&pool->ltp_cond);
+ done:
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(0);
return(-1);
}
+static void *
+no_task( void *ctx, void *arg )
+{
+ return NULL;
+}
+
+/* Cancel a pending task that was previously submitted.
+ * Return 1 if the task was successfully cancelled, 0 if
+ * not found, -1 for invalid parameters
+ */
+int
+ldap_pvt_thread_pool_retract (
+ ldap_pvt_thread_pool_t *tpool,
+ ldap_pvt_thread_start_t *start_routine, void *arg )
+{
+ struct ldap_int_thread_pool_s *pool;
+ ldap_int_thread_task_t *task;
+
+ if (tpool == NULL)
+ return(-1);
+
+ pool = *tpool;
+
+ if (pool == NULL)
+ return(-1);
+
+ ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
+ LDAP_STAILQ_FOREACH(task, &pool->ltp_pending_list, ltt_next.q)
+ if (task->ltt_start_routine == start_routine &&
+ task->ltt_arg == arg) {
+ /* Could LDAP_STAILQ_REMOVE the task, but that
+ * walks ltp_pending_list again to find it.
+ */
+ task->ltt_start_routine = no_task;
+ task->ltt_arg = NULL;
+ break;
+ }
+ ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
+ return task != NULL;
+}
+
/* Set max #threads. value <= 0 means max supported #threads (LDAP_MAXTHR) */
int
ldap_pvt_thread_pool_maxthreads(
case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
count = pool->ltp_open_count;
+ if (count < 0)
+ count = -count;
break;
case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
break;
case LDAP_PVT_THREAD_POOL_PARAM_PAUSING:
- count = pool->ltp_pause;
+ count = (pool->ltp_pause != 0);
break;
case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
struct ldap_int_thread_pool_s *pool;
if ( tpool != NULL && (pool = *tpool) != NULL ) {
- rc = pool->ltp_pause;
+ rc = (pool->ltp_pause != 0);
}
return rc;
return rc;
}
-static void
-flush_pending_list( struct ldap_int_thread_pool_s *pool )
-{
- ldap_int_thread_task_t *task;
-
- while ((task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL) {
- LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
- LDAP_FREE(task);
- }
-}
-
/* Destroy the pool after making its threads finish */
int
ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
SET_VARY_OPEN_COUNT(pool);
if (pool->ltp_max_pending > 0)
pool->ltp_max_pending = -pool->ltp_max_pending;
- if (!run_pending)
- flush_pending_list(pool);
+
+ if (!run_pending) {
+ while ((task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL) {
+ LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
+ LDAP_FREE(task);
+ }
+ pool->ltp_pending_count = 0;
+ }
while (pool->ltp_open_count) {
if (!pool->ltp_pause)
ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
}
- ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
-
- flush_pending_list(pool);
while ((task = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
{
LDAP_FREE(task);
}
+ ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
{
struct ldap_int_thread_pool_s *pool = xpool;
ldap_int_thread_task_t *task;
+ ldap_int_tpool_plist_t *work_list;
ldap_int_thread_userctx_t ctx, *kctx;
unsigned i, keyslot, hash;
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
pool->ltp_starting--;
+ pool->ltp_active_count++;
for (;;) {
- while (pool->ltp_pause)
- ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
-
- task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
- if (task == NULL) {
- if (pool->ltp_vary_open_count < 0) {
- /* not paused, and either finishing or too many
- * threads running (can happen if ltp_max_count
- * was reduced) so let this thread die.
- */
- break;
+ work_list = pool->ltp_work_list; /* help the compiler a bit */
+ task = LDAP_STAILQ_FIRST(work_list);
+ if (task == NULL) { /* paused or no pending tasks */
+ if (--(pool->ltp_active_count) < 2) {
+ /* Notify pool_pause it is the sole active thread. */
+ ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
}
- /* we could check an idle timer here, and let the
- * thread die if it has been inactive for a while.
- * only die if there are other open threads (i.e.,
- * always have at least one thread open). the check
- * should be like this:
- * if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
- * check timer, wait if ltp_pause, leave thread (break;)
- *
- * Just use pthread_cond_timedwait if we want to
- * check idle time.
- */
+ do {
+ if (pool->ltp_vary_open_count < 0) {
+ /* Not paused, and either finishing or too many
+ * threads running (can happen if ltp_max_count
+ * was reduced). Let this thread die.
+ */
+ goto done;
+ }
- ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
- continue;
+ /* We could check an idle timer here, and let the
+ * thread die if it has been inactive for a while.
+ * Only die if there are other open threads (i.e.,
+ * always have at least one thread open).
+ * The check should be like this:
+ * if (pool->ltp_open_count>1 && pool->ltp_starting==0)
+ * check timer, wait if ltp_pause, leave thread;
+ *
+ * Just use pthread_cond_timedwait() if we want to
+ * check idle time.
+ */
+ ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
+
+ work_list = pool->ltp_work_list;
+ task = LDAP_STAILQ_FIRST(work_list);
+ } while (task == NULL);
+
+ pool->ltp_active_count++;
}
- LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
+ LDAP_STAILQ_REMOVE_HEAD(work_list, ltt_next.q);
pool->ltp_pending_count--;
- pool->ltp_active_count++;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
task->ltt_start_routine(&ctx, task->ltt_arg);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, task, ltt_next.l);
- pool->ltp_active_count--;
- /* let pool_pause know when it is the sole active thread */
- if (pool->ltp_active_count < 2)
- ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
}
+ done:
+
+ assert(!pool->ltp_pause); /* thread_keys writable, ltp_open_count >= 0 */
/* The ltp_mutex lock protects ctx->ltu_key from pool_purgekey()
* during this call, since it prevents new pauses. */
pool->ltp_open_count--;
SET_VARY_OPEN_COUNT(pool);
/* let pool_destroy know we're all done */
- if (pool->ltp_open_count < 1)
+ if (pool->ltp_open_count == 0)
ldap_pvt_thread_cond_signal(&pool->ltp_cond);
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(NULL);
}
-/* Pause the pool. Return when all other threads are paused. */
-int
-ldap_pvt_thread_pool_pause (
- ldap_pvt_thread_pool_t *tpool )
+/* Arguments > ltp_pause to handle_pause(,PAUSE_ARG()). arg=PAUSE_ARG
+ * ensures (arg-ltp_pause) sets GO_* at need and keeps DO_PAUSE/GO_*.
+ */
+#define GO_IDLE 8
+#define GO_UNIDLE 16
+#define CHECK_PAUSE 32 /* if ltp_pause: GO_IDLE; wait; GO_UNIDLE */
+#define DO_PAUSE 64 /* CHECK_PAUSE; pause the pool */
+#define PAUSE_ARG(a) \
+ ((a) | ((a) & (GO_IDLE|GO_UNIDLE) ? GO_IDLE-1 : CHECK_PAUSE))
+
+static int
+handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
{
struct ldap_int_thread_pool_s *pool;
+ int ret = 0, pause, max_ltp_pause;
if (tpool == NULL)
return(-1);
if (pool == NULL)
return(0);
+ if (pause_type == CHECK_PAUSE && !pool->ltp_pause)
+ return(0);
+
+ /* Let pool_unidle() ignore requests for new pauses */
+ max_ltp_pause = pause_type==PAUSE_ARG(GO_UNIDLE) ? WANT_PAUSE : NOT_PAUSED;
+
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
- /* If someone else has already requested a pause, we have to wait */
- if (pool->ltp_pause) {
+ pause = pool->ltp_pause; /* NOT_PAUSED, WANT_PAUSE or PAUSED */
+
+ /* If ltp_pause and not GO_IDLE|GO_UNIDLE: Set GO_IDLE,GO_UNIDLE */
+ pause_type -= pause;
+
+ if (pause_type & GO_IDLE) {
pool->ltp_pending_count++;
pool->ltp_active_count--;
- /* let the other pool_pause() know when it can proceed */
- if (pool->ltp_active_count < 2)
+ if (pause && pool->ltp_active_count < 2) {
+ /* Tell the task waiting to DO_PAUSE it can proceed */
ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
- do {
- ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
- } while (pool->ltp_pause);
+ }
+ }
+
+ if (pause_type & GO_UNIDLE) {
+ /* Wait out pause if any, then cancel GO_IDLE */
+ if (pause > max_ltp_pause) {
+ ret = 1;
+ do {
+ ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
+ } while (pool->ltp_pause > max_ltp_pause);
+ }
pool->ltp_pending_count--;
pool->ltp_active_count++;
}
- /* Wait for everyone else to pause or finish */
- pool->ltp_pause = 1;
- SET_VARY_OPEN_COUNT(pool);
-
- while (pool->ltp_active_count > 1) {
- ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
+ if (pause_type & DO_PAUSE) {
+ /* Tell everyone else to pause or finish, then await that */
+ ret = 0;
+ assert(!pool->ltp_pause);
+ pool->ltp_pause = WANT_PAUSE;
+ /* Let ldap_pvt_thread_pool_submit() through to its ltp_pause test,
+ * and do not finish threads in ldap_pvt_thread_pool_wrapper() */
+ pool->ltp_open_count = -pool->ltp_open_count;
+ SET_VARY_OPEN_COUNT(pool);
+ /* Hide pending tasks from ldap_pvt_thread_pool_wrapper() */
+ pool->ltp_work_list = &empty_pending_list;
+ /* Wait for this task to become the sole active task */
+ while (pool->ltp_active_count > 1) {
+ ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
+ }
+ assert(pool->ltp_pause == WANT_PAUSE);
+ pool->ltp_pause = PAUSED;
}
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
- return(0);
+ return(ret);
+}
+
+/* Consider this task idle: It will not block pool_pause() in other tasks. */
+void
+ldap_pvt_thread_pool_idle( ldap_pvt_thread_pool_t *tpool )
+{
+ handle_pause(tpool, PAUSE_ARG(GO_IDLE));
+}
+
+/* Cancel pool_idle(). If the pool is paused, wait it out first. */
+void
+ldap_pvt_thread_pool_unidle( ldap_pvt_thread_pool_t *tpool )
+{
+ handle_pause(tpool, PAUSE_ARG(GO_UNIDLE));
+}
+
+/*
+ * If a pause was requested, wait for it. If several threads
+ * are waiting to pause, let through one or more pauses.
+ * The calling task must be active, not idle.
+ * Return 1 if we waited, 0 if not, -1 at parameter error.
+ */
+int
+ldap_pvt_thread_pool_pausecheck( ldap_pvt_thread_pool_t *tpool )
+{
+ return handle_pause(tpool, PAUSE_ARG(CHECK_PAUSE));
+}
+
+/*
+ * Pause the pool. The calling task must be active, not idle.
+ * Return when all other tasks are paused or idle.
+ */
+int
+ldap_pvt_thread_pool_pause( ldap_pvt_thread_pool_t *tpool )
+{
+ return handle_pause(tpool, PAUSE_ARG(DO_PAUSE));
}
/* End a pause */
return(0);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
+
+ assert(pool->ltp_pause == PAUSED);
pool->ltp_pause = 0;
+ if (pool->ltp_open_count <= 0) /* true when paused, but be paranoid */
+ pool->ltp_open_count = -pool->ltp_open_count;
SET_VARY_OPEN_COUNT(pool);
- if (!pool->ltp_finishing)
- ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
+ pool->ltp_work_list = &pool->ltp_pending_list;
+
+ ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
+
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(0);
}
void *ctx = NULL;
ldap_pvt_thread_key_getdata( ldap_tpool_key, &ctx );
- return ctx ? ctx : &ldap_int_main_thrctx;
+ return ctx ? ctx : (void *) &ldap_int_main_thrctx;
}
/*
projects / openldap / blobdiff